Commit 637d3847 authored by Peter Ujfalusi's avatar Peter Ujfalusi Committed by Mark Brown
Browse files

ASoC: core: Support for limiting the volume 



Add support for the core to limit the maximum volume on an
existing control.
The function will modify the soc_mixer_control.max value
of the given control.
The new value must be lower than the original one (chip maximum)

If there is a need for limiting a gain on a given control,
than machine drivers can do the following in their
snd_soc_dai_link.init function:

snd_soc_limit_volume(codec, "TPA6140A2 Headphone Playback Volume", 21);

This will modify the original 31 (chip maximum) to 21, so user
space will not be able to set the gain higher than this.

Signed-off-by: default avatarPeter Ujfalusi <peter.ujfalusi@nokia.com>
Acked-by: default avatarLiam Girdwood <lrg@slimlogic.co.uk>
Signed-off-by: default avatarMark Brown <broonie@opensource.wolfsonmicro.com>
parent 30578764

include/sound/soc.h

+2 −0
Original line number Diff line number Diff line
@@ -326,6 +326,8 @@ int snd_soc_get_volsw_s8(struct snd_kcontrol *kcontrol, 
	struct snd_ctl_elem_value *ucontrol);

int snd_soc_put_volsw_s8(struct snd_kcontrol *kcontrol,

	struct snd_ctl_elem_value *ucontrol);

int snd_soc_limit_volume(struct snd_soc_codec *codec,

	const char *name, int max);



/**

 * struct snd_soc_jack_pin - Describes a pin to update based on jack detection

sound/soc/soc-core.c

+39 −0
Original line number Diff line number Diff line
@@ -2237,6 +2237,45 @@ int snd_soc_put_volsw_s8(struct snd_kcontrol *kcontrol, 
}

EXPORT_SYMBOL_GPL(snd_soc_put_volsw_s8);



/**

 * snd_soc_limit_volume - Set new limit to an existing volume control.

 *

 * @codec: where to look for the control

 * @name: Name of the control

 * @max: new maximum limit

 *

 * Return 0 for success, else error.

 */

int snd_soc_limit_volume(struct snd_soc_codec *codec,

	const char *name, int max)

{

	struct snd_card *card = codec->card;

	struct snd_kcontrol *kctl;

	struct soc_mixer_control *mc;

	int found = 0;

	int ret = -EINVAL;



	/* Sanity check for name and max */

	if (unlikely(!name || max <= 0))

		return -EINVAL;



	list_for_each_entry(kctl, &card->controls, list) {

		if (!strncmp(kctl->id.name, name, sizeof(kctl->id.name))) {

			found = 1;

			break;

		}

	}

	if (found) {

		mc = (struct soc_mixer_control *)kctl->private_value;

		if (max <= mc->max) {

			mc->max = max;

			ret = 0;

		}

	}

	return ret;

}

EXPORT_SYMBOL_GPL(snd_soc_limit_volume);



/**

 * snd_soc_dai_set_sysclk - configure DAI system or master clock.

 * @dai: DAI

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